HIV/AIDS Flashcards
What group of viruses does HIV belong to?
retroviridae group
How does the virus replicate within infected host cells?
Carries RNA genome and a reverse transcriptase enzyme (RNA-directed DNA polymerase)
How does HIV infect cells?
Affinity for binding to specific cell surface receptor molecule (CD4+)
What cell count do you monitor in HIV to monitor dz progress?
CD4+
MC mode of infection for HIV
sexual transmission across exposed mucosal epithelium
Viral pathogenesis
~ Proliferation of infected CD4+ T lymphocytes + migration of infected macrophages = appearance of viral RNA in bloodstream
~Widespread secondary amplification of infection within lymphoid tissue of:
- Gastrointestinal tract (Peyer’s patches)
- Spleen
- Bone marrow
Viral pathogenesis results
- Depression of functional capacity of T lymphocytes
- Depletion of helper T cells
- Impairment of killer T cell action
- Increased suppressor T cells
Who should be tested for HIV?
- all people 15-65 regardless of risk, at least once
- all pregnant women prior to childbirth
- younger/older individuals with increased risk factors
Initial testing of HIV
FDA-approved 4th-generation antigen/antibody combination immunoassay – detects HIV-1 & HIV-2 antibodies and HIV-1 p24 antigen
What is no longer recommended for HIV testing
ELISA, HIV-1 Western blot, and HIV-1 IFA no longer part of recommended algorithm
HIV Serology CD4 cell count
- The best measure of the status of the immune system and disease progression
- Demonstrates the risk of opportunistic infections
- Helps determine when to start antiretroviral therapy and PCP prophylaxis; also helps in evaluating the immune system’s response to this therapy
- If untreated, CD4 count declines at a rate of approximately 50 cells per year
HIV CD4 counts >500 cells
- minimal compromise in the immune system and the threat of HIV-related infection or illness is marginal
CD4 count 200-500
- risk of HIV-related conditions, such as herpes zoster, TB, lymphoma, bacterial pneumonias, and Kaposi sarcoma, increases
CD4 count <200
- when most of the opportunistic infections that define AIDS present
HIV viral load is used to measure…
- measure the response to and efficacy of HAART; gives corresponding predictive information to the CD4 count
- If the viral load is still > 50 after 4 months of therapy, regimen modification may be needed
Acute infection of HIV
- Initially appears with a syndrome similar to that seen with mononucleosis
- Occurs about 2-4 weeks after exposure to HIV
- Sx consistent with flu/mono
- this duration is brief: 3 days to 2 wks
ASx/Latent infection of HIV
- Seropositive: no Signs/Sx of HIV infection
- Normal CD4 count
- Longest phase: lasting 4-7 yrs
Symptomatic infection of HIV
- “Pre-AIDS”
- 1st notice of immunocompromised state
- Phase length tends to vary with efficacy of tx and condition of immune system
Neurologic Sx of HIV infection symptoms
- meningitis
- encephalitis
- peripheral neuropathy
- myelopathy
Dermatological Sx of HIV infection symptoms
- erythematous maculopapular rash
- mucocuatneous ulceration
Sx HIV infection clinical manifestations
- Persistent generalized lymphadenopathy
- Localized fungal infections (e.g., onychomycosis, thrush)
- Intractable vaginal yeast and trichomonal infections in females
- Oral hairy leukoplakia on the tongue
- Dermatologic conditions: seborrheic dermatitis, psoriasis exacerbations, molluscum contagiosum, warts
- Constitutional symptoms: night sweats, weight loss, diarrhea
Clinical manifestations of AIDS
- Marked immune suppression
- Onset of disseminated opportunistic infections and malignancies
- CD4 count < 200/mm3
Sexual transmission of HIV
- MC mode of transmission
- No cases of transmission from saliva or tears documented
- Highest risk: unprotected anal receptive intercourse
- Latex condoms: reduce risk by 70-80%
- oral sex can result in transmission of HIV/STI’s
Needle sharing modes of transmission
- Risk of sustaining HIV infection from a needle stick with infected blood = 1 in 300
- Behavior can increase risk (needle sharing, “booting” the injection with blood, and performing frequent injections)
- Crack cocaine use (the injection or smoking) is associated with increased prevalence of HIV infection (cocaine for sex bartering)
- Secondary transmission occurs to children and sexual partners